Communication mechanisms exist on many online platforms. For example, standardized mechanisms allow users to receive email messages from any message sender who inputs an email address associated with the message receiver. Apart from email, social network services and many content hosting services allow users to communicate with one another, either by private message (e.g., delivered to an internal inbox associated with an account of the message receiver) or posted to a feed or comments section associated with content (e.g., text, images, video, etc.) published by the message receiver.